1. Field of the Invention
The present invention relates to a machining device equipped with a spindle position interchanger, and a method for interchanging spindle positions.
2. Description of the Related Art
The outline of an example of a conventional machining center is shown in FIGS. 8 and 9. As shown in FIGS. 8 and 9, this machining center comprises a longitudinal table 02 provided on a bed 01 and movable in a horizontal direction, a transverse table 03 provided on the longitudinal table 02 and movable in a direction perpendicular to the table 02, a column 04 erected on the transverse table 03, a spindle head 05 vertically movable along the column 04, a main spindle 06 attached to the spindle head 05, a tool change arm 08 for changing a tool 07 in the main spindle 06, and a tool magazine 010 housing many tools 09. In FIG. 9, the reference numeral 031 denotes a base plate for the bed, 032 denotes a ball screw and a support bearing, 033 denotes an X-axis slide cover, 034 denotes a Z-axis rear slide cover, 035 denotes a spindle and a motor, 036 denotes an ATC motor, 037 denotes a strut, and 038 denotes a control panel.
The above-described machining center has the main spindle 06, the tool change arm 08 adapted for the main spindle 06, andthemagazineolo storing the tools 09. Thus, this machining center can perform various types of machining one after another while changing the tool 07 in the main spindle 06 for a selected tool 09 in the tool magazine 010 by the use of the tool change arm 08. This tool change is carried out by moving the spindle head 05 to a predetermined tool change position, stopping rotation of the main spindle 06, gripping both of the tool 07 in the main spindle 06 and the tool 09 in the tool magazine 010 by the tool change arm 08, and turning the tool change arm 08. After completion of this tool change, the main spindle 06 is restarted. After a wait until the main spindle 06 reaches a predetermined revolution speed, a subsequent machining operation is performed.
In connection with the tool change, the following actions occur on the main spindle 06: {circle around (1+L )} Stoppage (deceleration) of the main spindle 06, {circle around (2+L )} change from the tool 07 in the main spindle 06 to the tool 09 selected from within the tool magazine 010, and {circle around (3+L )} restart (acceleration) of the main spindle 06 after tool change. Periods of time required for these actions are added one to another sequentially.
How to reduce the times for the actions has been studied to ensure high efficiency and increased productivity on a machining line for mass production. However, the main spindle is present at one site only, so that the main spindle rotating at a high speed needs to be stopped. Thus, it has been difficult to shorten the time necessary for tool change. Particularly, as the frequency of tool change increases, this tool change time is accumulated, resulting in a decrease in productivity. To shorten the machining time, it is required to make the rotation of the main spindle as fast as possible. However, the time necessary for deceleration or acceleration is prolonged, failing to fulfill the requirement for reduction of the tool change time.
With a conventional machining device, therefore, a proposal has been made to provide two main spindles on a machining side, as shown in FIG. 10, and to move and control these main spindles individually. As illustrated in FIG. 10, this machining device has two spindle heads 025, 026 vertically movable along columns 023, 024 by respective feed motors 021, 022, and has main spindles 027, 028 installed on the spindle heads 025, 026. A tool magazine 029 is common to the main spindles 027, 028, and indexing and longitudinal movement of the tool magazine 029 result in the change of respective tools. A workpiece is mounted on a table 030.
Such a machining device has the two main spindles provided on the machining side in changing tools. Thus, the movement of the tools during tool change may induce interference with the workpiece, thereby limiting the timing of tool change. Furthermore, the spindle heads 025, 026 are present for the columns 023, 024, respectively, thus upsizing the entire machining device, and making the area of installation large. In addition, the distance between the two main spindles diminishes the effective moving distance to and from the workpiece.
The present invention has been accomplished to solve the foregoing problems with the earlier technologies.
According to a first aspect of the present invention, there is provided a machining device equipped with a spindle position interchanger, which has a spindle head vertically movably mounted on a moving column horizontally moving in longitudinal and transverse directions, the machining device comprising a turret unit provided on the spindle head rotatably about a turning axis; a plurality of main spindles provided on the turret unit, positions of the main spindles being interchangeable by rotation about the turning axis; spindle drive motors coupled to the respective main spindles; and a tool changer for performing tool change for the main spindle located at anon-machining position. Thus, even during indexing for spindle position interchange, the tool in the main spindle can keep rotating. Hence, during machining using a certain main spindle, the tool in another main spindle can be rotated beforehand, and can be put into machining immediately after indexing for the main spindle. Consequently, the non-cutting time can be decreased, the cycle time for machining can be shortened, so that productivity per machining device is increased. Using the same number of the machining devices of the present invention as the number of the conventional machining devices will make increased production possible. On condition that the same amount of work is to be machined, the use of the machining device of the present invention can decrease the required number of the machining devices.
According to a second aspect of the present invention, there is provided a method for interchanging spindle positions in a machining device equipped with a spindle position interchanger, the machining device having two or more main spindles connected to spindle drive motors, and the machining device including the spindle position interchanger for interchanging positions of the two or more main spindles by rotation about a turning axis, and a tool changer for changing a tool for at least one of the main spindles, the method comprising performing machining with the use of one of the main spindles, while changing a tool mounted on a different one of the main spindles; then starting rotation of the different main spindle; and then interchanging positions of the one main spindle and the different main spindle by rotation about the turning axis. Furthermore, machining is immediately started by use of the tool in the different main spindle after spindle position interchange. Thus, the time for tool change done while stopping the rotation of the main spindle, as in the earlier technology, becomes unnecessary. Moreover, if the revolution speed of the main spindle having a tool, which will replace the tool in current use for machining, is raised to a predetermined revolution speed before spindle position interchange, machining can be immediately started after spindle position interchange, so that the non-machining time can be reduced markedly.
According to a third aspect of the present invention, there is provided a method for interchanging spindle positions in a machining device equipped with a spindle position interchanger as recited in the second aspect, wherein the one main spindle during machining is provided so as not to interfere with the different main spindle when the tool is changed. Thus, tool change can be performed on the side opposite to the side on which machining is carried out. There is no interference between a workpiece and actions associated with tool change, so that the timing of change is not restricted.
According to a fourth aspect of the present invention, there is provided a method for interchanging spindle positions in a machining device equipped with a spindle position interchanger as recited in the second or third aspect, wherein the spindle position interchanger interchanges the positions of the two or more main spindles by rotating the two or more main spindles about the turning axis which is vertical. Thus, it is easy to interchange the positions of the main spindles, a space for turning is narrow, and space saving can be ensured.
According to a fifth aspect of the present invention, there is provided a method for interchanging spindle positions in a machining device equipped with a spindle position interchanger as recited in the second or third aspect, wherein the spindle position interchanger changes the positions of the two or more main spindles by rotating the two or more main spindles about the turning axis which is horizontal. Thus, the positions of the main spindles are easy to interchange.
According to a sixth aspect of the present invention, there is provided a method for interchanging spindle positions in a machining device equipped with a spindle position interchanger as recited in the fourth or fifth aspect, wherein the main spindles are perpendicular to or parallel to the turning axis. Thus, it becomes easy to arrange the main spindles.
According to a seventh aspect of the present invention, there is provided a method for interchanging spindle positions in a machining device equipped with a spindle position interchanger as recited in the fourth or fifth aspect, wherein the main spindles make arbitrary angles to the turning axis. Thus, it becomes easy to arrange the main spindles.
According to an eighth aspect of the present invention, there is provided a machining device equipped with a spindle position interchanger, comprising a moving column horizontally movable in longitudinal and transverse directions on a bed; a spindle head vertically movably mounted on the moving column; a turret unit provided on the spindle head rotatably about a turning axis; a plurality of main spindles provided on the turret unit, positions of the main spindles being interchangeable between a machining position and a non-machining position by rotation about the turning axis, and the main spindles being arranged at positions twisted relative to the turning axis; spindle drive motors coupled to the respective main spindles; and an automatic tool changer having a tool change arm for performing tool change for the main spindle located at the non-machining position. According to this aspect, the distance between the main spindles is so small that the entire machining device is compact in size.